Blast From the Past

Summary of the May 18, 1980, eruption of Mt. St. Helens:

* First sign of activity: A series of small earthquakes on March 16.

* More than 10,000 earthquakes recorded by May 17, a day before the eruption.

* Elevation before the eruption: 9,677 feet. Elevation after the eruption: 8,363 feet (a difference of 1,314 feet).

* Landslide moved 70 mph to 150 mph, covered 23 square miles and buried 14 miles of the North Fork Toutle River Valley to an average depth of 150 feet and a maximum of 600 feet.

* Lateral blast covered 230 square miles, reaching 17 miles northwest of the crater.

* Blast moved at a velocity of at least 300 mph with temperatures as high as 660 degrees Fahrenheit.

* Blast blew down 4 billion board-feet of timber, enough to build about 300,000 two-bedroom homes.

* Ash column rose more than 15 miles into the atmosphere in less than 15 minutes. Prevailing winds blew an estimated 520 million tons of ash eastward across the United States.

* Volcanic mudflows known as lahars damaged 27 bridges and nearly 200 homes and stranded 31 ships on the Columbia River.

* 57 people died.

* Countless animals in the blast area died, including about 7,000 big-game animals such as elk, and about 12 million salmon fingerlings in hatcheries.